Copper River and Knik River Bathymetric Surveys at Select Alaska Highway Bridges near Flag Point and Butte, Alaska, 2020

In 2020, the Alaska Science Center and the Idaho Water Science Center conducted bathymetric surveys at three highway bridge structures. The bridge structures (NBI 331 and 1187) at Flag Point near Cordova, AK are located on Alaska State Route 10 (commonly referred to as the Copper River Highway). Bridge structure NBI 539 on the Knik River is located on the Old Glenn Hwy near Butte, AK. These bathymetry data generally include complete coverage for upstream and downstream channels, except for extreme shallow areas along banks, where structures limited boat access, or where data was removed during post-processing. Bridges 1187, 331, and 539 are scour-critical bridges, and 1187 and 539 are part of the Alaska Science Center's real-time bridge scour monitoring program. High-resolution bathymetric data were requested to provide representation of streambed elevations near the bridge foundations to better evaluate scour and sediment transport in each reach.